This training grant provides research training that will allow M.D., Ph.D., and M.D./Ph.D postdoctoral fellows to become independent investigators in the fields of diabetes, obesity, and metabolism. Research training will be provided by a large group of highly skilled and experienced investigators at the University of Washington and affiliated institutions who will serve as preceptors. Based on 1) the continued outstanding success of this program and large numbers of applicants, 2) an expanded emphasis on basic science aspects of obesity and diabetes, 3) a major new commitment from the University of Washington to create and support a Diabetes and Obesity Center of Excellence in a new research campus, and 4) a substantial increase in the size of our program faculty, we request an increase in the number of training slots from four to six. M.D. candidates will have completed residency training as well as a first, clinical year of fellowship prior to funding via this program. This arrangement allows both M.D. and Ph.D. fellows to spend at least 80% of their time on research activities while they are supported by this training grant. Selection of fellow applicants will be done by the Fellowship Training Executive Committee, and will benefit from a large pool of qualified candidates who apply to the Division of Metabolism, Endocrinology and Nutrition at the University of Washington for their research training. Among the criteria for selection are 1) a strong interest in the fields of diabetes, obesity and glucose or energy metabolism (frequently accompanied by previous research experience) and 2) demonstrated potential for a successful research career. This program provides trainees with research experience in both basic and clinical aspects of diabetes and obesity, with special emphasis on molecular and cell biology, physiology, and translational research. Research training will be complemented by didactic lectures and seminars that cover diabetes, obesity, glucose homeostasis, energy metabolism and related aspects of endocrinology, with additional seminars on scientific methods, manuscript preparation, grantsmanship, and biomedical ethics. Diabetes and obesity are among the most pressing public health concerns. Despite impressive advances at the basic science level, major unanswered questions regarding the pathogenesis of these disorders continue to limit our capacity to treat them. Effective training for scientists in obesity and diabetes is therefore a fundamental priority.